Shylock often references the anti-semetic treatment he has received throughout the play. While this is the obvious answer to this question, it is not simple anti-semeticism to which he refers. Shylock also references his deep religious values and personal spirituality. His Biblical stories he references not in spite, but in deep rooted belief and one must almost feel a sense of sincere sympathy for him. He is not acting purely in a veangeful manner, but in accordance with what he believes to be divine spiritual law and his inner belief system. This is also why he references the loss of his daughter through her betrayal and conversion to the Christian faith so frequently.
Shylock often shows his concern with money, but also his resentment concerning how he is treated by the Christians, and sometimes he shows a humanity that is difficult for the audience not to respond to with compassion. His speech in 3.1 where he clearly says he wants revenge indicates how much he resents the way people mistreat him. "He [Antonio] hath disgraced me and hindered me half a million, laughed at my losses, mocked at my gains, scorned my nation....," says Shylock to Salarino, showing how deeply he resents their treatment of him. He then insists on his humanity: "Hath not a Jew eyes? Hath not a Jew hands, organs..." When he discovers his daughter has run away with his money, we see how avaricious he is. "My ducats, my daughter!" he exclaims, causing us to think, perhaps, that he values his money as much as or perhaps more than he does his daughter.
we can not deny that shylock is a violent character in the play,wants a pound of Antonio`s flesh, lends by interest, looking for revenge, but why?may be for that in his nature or for he was fed by the haterd of the christians. Shakespeare may guide his audience to a serious and dangerous issue that if they keep treat the jewish in that society in this way after a while all the jewish will be shylock.
I think that people will not Transcends to the idea of freedom even if they pretend that, the only thing that all the people on the planet share is humanity.
Unfortunately, some can not understand it`s meaning.